[192862] in North American Network Operators' Group
Re: 10G switch drops traffic for a split second
daemon@ATHENA.MIT.EDU (Michael Loftis)
Tue Nov 29 16:47:54 2016
X-Original-To: nanog@nanog.org
In-Reply-To: <CAP5r2ctOm1v8axHrUqMz5jcov2gdgJ7VD3bE=a4MCMUe0A3Vbw@mail.gmail.com>
From: Michael Loftis <mloftis@wgops.com>
Date: Tue, 29 Nov 2016 13:47:49 -0800
To: TJ Trout <tj@pcguys.us>
Cc: nanog <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
Yes it is absolutely possible to overrun the buffers. Any kind of
backpressure (FC) from hosts, or 10G->1G transitions can easily cause
it. Even if in a 10s window you're not over 1G if the 10G sender
attempts to back to back too many frames in a row (Like say sendfile()
API type calls) BOOM, dropping frames in the switch.
On Tue, Nov 29, 2016 at 1:28 PM, TJ Trout <tj@pcguys.us> wrote:
> Luke;
>
> All l2, no l3. only 4 vlans. 2 peers trunked to a router which trunks back
> to 2 devices (microwave backhauls).
>
> Chuck;
>
> All ports are 10g except the 2 peers are 1g and trunk back to a 10g port
> for the router wan
>
> No TCN's
>
> Brian;
>
> I have tried a IBM G8124 and a Ubiquiti ES-16-XG both show same exact drops
> across all ports, makes me think it's a config issue. MTU, FC, something.
>
> Andrew;
>
> I have tried with FC disabled, but I will try that one more time.
>
> Mikael;
>
> Is it possible to over run the buffers of a 320gbps backplane switch with
> only 1.5gbps traffic? I think the switch is rated for 140m PPS and I'm only
> pushing 100k PPS
